6to4 allows devices on separate IPv6 networks to communicate with each other across an IPv4 network. It does this by encapsulating the IPv6 data packet as the payload of an IPv4 packet. 6to4 addresses always begin with the prefix 2002::/16. When communicating across an IPv4 network, an IPv4 source and destination address must be used. This is obtained by the transmitting device by looking at the next 32 bits that follow the 2002 prefix in the IPv6 addresses being used.

While the preceding sounds reasonably straightforward, we have to bear in mind that there needs to be a supporting infrastructure in place including 6to4 routers, as well as a public IPv4 address for each endpoint. Also, it does not work for devices that are sitting behind ...

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